The human body comprises a very large number of articulations ensuring the junction between bones or limbs of the body. There are, for example, approximately forty articulations in a lower human limb, from the hip to the ankle. These articulations are mobile by means of muscles, and take various forms to allow varied movements. Numerous attempts have been made in humanoid-type robots to best reproduce the behavior and the movements of a human being. Various types of articulations are known that are capable of moving by means of an electric motor one limb relative to another according to one or more degrees of freedom.
One difficult situation is that of an electrical power outage that can for example occur due to a computer error or a loss of battery charge. With the drive by the electric motor being interrupted, the articulation is free and the robot is liable to fall. This situation is all the more difficult when the robot is large in size and very heavy. With a view to widespread use by any consumer, efforts are made to improve the safety of use of the humanoid robots.